Manufacture of resilient springs



July 16, 1940. R. c. PIERCE 2,208,052

MANUFACTURE OF RESILIENT SPRINGS Original Filed April 17, 1936 QQQQ Q ge yam. 2:-

my. 3 Fig. 4 Hg. '6 my. 7 Q 42 5 INVENTOR. ROBERT C 515%.:

ATTORNEYS.

Patented July 16, 1940 MANUFACTURE OF RESILJENT SPRINGS Robert Pierce,Niles, Mich.,

assignor to National Standard Company, Niles, Mich, a corporation ofMichigan Original application April 17, 1936, Serial No.

74,844, now Patent No. 2,137,698, dated November 22, 1938. September 29,1938,

4 Claims.

This invention relates to springs and method of making the same and moreparticularly to resilient springs made of an open mesh braid of steelwire or the like.

One of the objects of the invention is to provide a simple and fastmethod of forming springs of braided wire. According to one importantfeature a wire braid is spread to form relatively sharp reverse bends inthe wire at the edges of the braid and the wires are then permanentlyset to form a series of small springs.

Another object of the invention is to provide a spring formed of braidedwires having reverse bends at the edges of the braid to form smallresilient portions. The total resilience of the spring in thisconstruction is the sum of the resilience of all of the reverse bends.

Other objects, advantages and novel features of the invention will beapparent from the following description of the accompanying drawing inwhich:

Figure 1 is an exaggerated plan view of a spring according to theinvention showing portions incompleted;

Figure 2 is a diagram in side elevation illustrating the method ofmanufacture;

Figures 3, 4 and 5 are sections showing, before compression, fromdifierent points of view, one of the reverse bends of the wire at oneedge of the braid; and

Figures 6, 7 and 8 are similar views showing the bend after compression.

The spring of the present invention is formed of a flat braid ll) ofwires passing alternately over and under each other diagonally acrossthe braid with relatively flat reverse bends at the edges of the braidand with all of the wires extending the full length of the braid. Thewires are preferably of cold-drawn high carbon steel, which can be setin the desired spring formation by compressing the bends at the edges ofthe braid beyond the elastic limit of the steel, Without furthertreatment. Good results can be obtained, however, by using lower carbonsteel such as .45% or 50% carbon steel and tempering it aftercompression by heating it and quenching it in oil.

In carrying out the method the braid is first spread to increase thesharpness of the reverse bends as indicated at I2 and while so spread iscompressed beyond the elastic limit of the wire to set the bends.Preferably the braid is spread beyond its ultimate width as shown at Mand after compression is allowed to spring back slightly to its ultimatewidth as shown at I6.

Divided and this application Serial No. 232,265 (01. 140-107)- performedby spaced sets of rolls l8 and 20 engaging the flat sides of the braidand driven in the same direction with the rolls l8 turning faster thanthe rolls 20. This causes the braid to be compressed lengthwise tospread it width- Wise, suitable guides, not shown, preferably beingprovided between the sets of rolls to prevent the braid from buckling.The rolls 20 engage the braid with a heavy pressure to compress thereverse bends at the edges of the braid beyond the elastic limit of thewire to set them so that the braid will permanently retain its spreadshape. These rolls 20 may be faced with rubber or the like which willyield sufiiciently where the wires cross each other to insure that theedges will be adequately compressed or may be of reduced diameter attheir center portions as more fully disclosed in my copendingapplication, Serial No. 74,844, filed April 1'7, 1936 of which thisapplication is a division.

As illustrated more fully in Figs. 3 to 8, the reversed bends 12 priorto compression are in the form of partial loops and the compression stepflattens these loops into the plane of the braid and at the same timestresses the wires beyond their elastic limit so that they will take apermanent set. After compression, the braid has the permanent spreadform indicated at l6 and is elastic in tension, its resilience being thesum of the resilience of all of the reverse bends. If a low carbon steelwire has been used, the braid is tempered after compression by beingheated and quenched in oil.

If desired the spreading operation may be interrupted periodically alongthe length of the braid by periodically separating the rollers 20 toprovide unspread portions through which the braid may be cut and whichmay be used for connection to suitable fastening devices.

While one embodiment of the invention has been illustrated and describedin detail, it is not intended to limit the scope of the invention bythat description nor otherwise than by the terms of the appended claims.This application is a division of my copending application Serial No.74,844 filed April 1'7, 1936, now matured into Patent No. 2,137,698issued November 22, 1938 which is in turn a continuation in part of mycopending application Serial No. 41,199 filed September 19, 1935.

What is claimed is:

1. The method of making a resiliently extensible spring which comprisesforming an openmesh braid of wires passed alternately over and Thespreading and compressing steps may be under each other diagonallyacross the braid and formed at the edges of the braid with reversebends, and compressing said bends heavily enough permanently to setthem, whereby the braid forms a spring structure whose resilience is thesum of the spring action of all of said set" bends.

2. That method of making a resiliently extensible spring which comprisesforming an openmesh braid of wires passed alternately over and undereach other diagonally across the braid and formed at the edges of thebraid with reverse bends, and spreading said braid to a width slightlygreater than the desired final width of the spring, compressing saidbends while the braid is so spread heavily enough permanently to setthem, and allowing the braid to contract width- Wise to its naturalwidth, whereby the braid forms a spring structure whose resilience isthe sum of the spring action of all of said set bends.

3. That method of making a resiliently extensible spring which comprisesforming a flat braid of wires passed alternately over and under eachother diagonally across the braid, compress ing said braidlongitudinally to spread it laterally and open up the braid so that thewires take relatively sharp reverse bends at the edges of the braid, andstressing said reverse bends beyond the elastic limit of the wire whilethe braid is so spread to set them whereby the braid forms a springstructure whose resilience is the sum of the resilience of all of saidset bends.

4. A resiliently extensible spring comprising an open-mesh braid ofsteel wires passing alternately over and under each other diagonallyacross the braid and having each wire bent back at the points where itreaches the edges of the braid in permanently-set spring bendscompressed beyond the elastic limit of the steel to bring the parts ofthe wire substantially into a plane, such bends forming spring elementswhose total resilience is the resilience of the spring.

ROBERT C. PIERCE.

